ok... been a while since i posted on here. I've had great sucess in the past. If anyone has followed me I've grown raskal's OG as my favorite strain and been very successful. 22% thc with great yields... almost the same setup. I've moved and have a slightly different setup but still run a RDWC. New strain that the wonderful state of WA has not seen is called sweet and sour white widdow... going to rock the recreational world... can't be happier about living in WA. I've always kept my 24/7 meter in the control bucket. But my new system the cotrol is the same size as the sites. I have a 4 site RDWC each bucket is 5 gallons with one control. I've kept my meters in the control but my numbers keep fluctuation like crazy.... the ppm fluctuates... not the ph or temp. I moved my ppm to one of the main buckets... and now it seems to fluctuate only when i open the tent. Can anyone explain to me why with negative pressure in my tent the ppm's jump by almost 300?? http://s244.photobucket.com/user/astral_design/media/PPMhelP.mp4.html?sort=3&o=0 not sure how to imbed video... give me a few.